Process for the preparation of substantially amorphous alpha-olefin polymers and compositions containing them and process for the preparation of bridged ligand

ABSTRACT

Amorphous polymers of alpha-olefins, particularly of propylene, having high molecular weights and narrow molecular weight distributions, in which the isotactic sequences are more abundant than the syndiotactic ones, can be obtained in high yields at temperatures of industrial interest by carrying out the polymerization reaction in the presence of metallocene catalysts comprising particular bridged bis-indenyl compounds substituted in the 3-position on the indenyl groups. The obtained amorphous polymers are particularly useful for the preparation of miscible compositions with substantially isotactic alpha-olefins.

The present invention relates to a process for the preparation ofsubstantially amorphous polymers of alpha-olefins. In particular, thepresent invention relates to a process for the preparation ofsubstantially amorphous homo- and copolymers of propylene andcompositions containing them together with isotactic polypropylene. Thepresent invention relates also to a convenient process for thepreparation of indenyl compounds useful for the preparation ofmetallocenes, which are used in the process for the preparation ofsubstantially amorphous polymers of alpha-olefins.

Products of the propylene homopolymerization can be either crystallineor amorphous. Whereas the polypropylene having isotactic or syndiotacticstructure is crystalline, the polypropylene having essentially atacticstructure is amorphous.

Amorphous polypropylene finds applications as a component in hot meltadhesives, paper coatings and as a bitumen additive. Generally, it canbe obtained as a side product from the preparation of isotacticpolypropylene in the presence of heterogeneous Ziegler-Natta typecatalysts. This product, however, has moderate molecular weight, broadmolecular weight distribution, and contains some residual cristallinity.Moreover, the separation of the fraction of amorphous polypropylene fromthe remainder product involves an additional step of separation by meansof solvents.

For use in a wider range of applications, notably in blends withcrystalline polypropylene for PVC replacement, amorphous polypropylenehaving high molecular weight is required.

More recently, by polymerizing propylene in the presence of particularmetallocene catalysts, amorphous polymers of propylene endowed with highmolecular weights and a narrow molecular weight distribution have beenobtained.

European patent application 604 917, for example, describes amorphouspropylene polymers obtained in the presence of bridged bis-fluorenylmetallocenes. The structure of the polymers is substantially atactic,with the syndiotactic dyads being more numerous than the isotacticdyads.

In International application WO 95/00562 it is described a process forproducing amorphous poly-alpha-olefins with a monocyclopentadienyltransition metal catalyst system. Both low and high molecular weightpolymers can be obtained, with narrow molecular weight distributions. Asfor the polymers described in EP-A-604,917, also in this case thesyndiotactic dyads are more abundant than the isotactic dyads.

These amorphous polymers of propylene find interesting applications inblends with cristalline polyolefins.

In International application WO 96/23838, for instance, there aredescribed blends of high molecular weight amorphous polypropylene withlower molecular weight isotactic polypropylene. The amorphouspolypropylene, which are produced by using the same catalyst as inWO95/00562, have more syndiotactic than isotactic dyads.

It would be desirable to make available amorphous alpha-olefin polymersendowed with high molecular weights and narrow molecular weightdistributions, which are more miscible with isotacticpoly-alpha-olefins. It would also be desirable to provide amorphousalpha-olefin polymers with improved elastomeric properties.

In European patent application EP-A-0 693 506 the preparation ofsubstantially amorphous polymers of propylene in the presence ofunbridged bis-indenyl or bis-4,5,6,7-tetrahydroindenyl compoundssubstituted in the 2-position on the indenyl or tetrahyroindenyl groupsis described. In these polymers, the isotactic dyads are more numerousthan the syndiotactic dyads. However, when the polymerization is carriedout at temperatures of industrial interest, polymers of propyleneendowed with low molecular weight are obtained.

In European patent application EP-A-0 584 609 it is described thepreparation of polypropylene by means of a metallocene compound, whichis used as a mixture of its racemic and meso isomeric form. The obtainedpolypropylene compositions contain fractions of amorphous and isotacticpolypropylene. The miscibility of those fractions can still be improved.

U.S. Pat. No. 5,516,848 and U.S. Pat. No. 5,539,056 relate to the insitu preparation of polypropylene blends comprising high molecularweight amorphous polypropylene with lower molecular weight isotacticpolypropylene. It is mentioned that blends containing low molecularweight amorphous polypropylene with high molecular weight isotacticpolypropylene have poor elastic recovery properties, due to thestiffness of the isotactic polypropylene.

It has been surprisingly found that it is possible, operating atconditions of industrial interest, to prepare amorphous polymers ofalpha-olefins having high molecular weights, narrow molecular weightdistribution, with a predominance of isotactic dyads, by carrying outthe polymerization reaction in the presence of metallocene catalystscomprising a particular substituted, single-atom-bridged, bis-indenylcompound.

Therefore, the present invention provides a process for the preparationof polymers of alpha-olefins, particularly of propylene, in the presenceof a catalyst comprising the product obtainable by contacting:

(A) a metallocene compound in the racemic form of the formula (I):

 wherein

substituents R¹ are hydrogen atoms;

R² and R³ are, independently from each other, C₁-C₂₀-alkyl,C₃-C₂₀-cycloalkyl, C₂-C₂₀-alkenyl, C₆-C₂₀-aryl, C₇-C₂₀-alkylaryl orC₇-C₂₀-arylalkyl radicals, optionally containing silicon or germaniumatoms;

or where R² and R³ can be joined together to form a 4 to 6 membered ringor a 6 to 20 fused ring system;

R⁴ and R⁵, same or different, are hydrogen atoms or —CHR⁸R⁹ groups;

R⁴ and R⁵ can form a ring having 3 to 8 carbon atoms, which can containhetero atoms;

the R⁸ and R⁹ substituents, same or different, are hydrogen atoms,C₁-C₂₀-alkyl, C₃-C₂₀-cycloalkyl, C₂-C₂₀-alkenyl, C₆-C₂₀-aryl,C₇-C₂₀-alkylaryl or C₇-C₂₀-arylalkyl radicals, which can form a ringhaving 3 to 8 carbon atoms which can contain hetero atoms;

the R⁶ and R⁷ substituents, same or different, are hydrogen,C₁-C₁₀-alkyl, C₃-C₂₀-cycloalkyl, C₂-C₂₀-alkenyl, C₆-C₂₀-aryl,C₇-C₂₀-alkylaryl or C₇-C₂₀-arylalkyl radicals, optionally containingsilicon or germanium atoms; and optionally two adjacent R⁶ and R⁷substituents can form a ring comprising from 5 to 8 carbon atoms;

M is a transition metal selected from those belonging to group 3, 4, 5,6 or to the lanthanide or actinide groups in the Periodic Table of theElements (new IUPAC version), X, same or different, is a monoanionicligand, such as a hydrogen atom, a halogen atom, a R¹⁰, OR¹⁰, OSO₂CF₃,OCOR¹⁰, SR¹⁰, NR¹⁰, or PR¹⁰ ₂ group, wherein the substituents R¹⁰ are aC₁-C₂₀-alkyl, C₃-C₂₀-cycloalkyl, C₂-C₂₀-alkenyl, C₆-C₂₀-aryl,C₇-C₂₀-alkylaryl or C₇-C₂₀-alkylaryl radical, optionally containingsilicon or germanium atoms;

p is an integer from 0 to 3, p being equal to the oxidation state of themetal M minus two; and

(B) an alumoxane and/or a compound capable of forming an alkylmetallocene cation.

In the metallocene of formula (I) the transition metal M is preferablyselected from titanium, zirconium and hafnium.

More preferably, the transition metal M is zirconium.

The X substituents are preferably chlorine atoms or methyl groups.

The R⁶ and R⁷ substituents are preferably hydrogen atoms.

Non-limiting examples of metallocene compounds of formula (I) suitablefor use in the process of the invention are:

methylene-bis(3-isopropyl-indenyl)zirconium dichloride and dimethyl;

isopropylidene-bis(3-isopropyl-indenyl)zirconium dichloride anddimethyl;

cyclopentylidene-bis(3-isopropyl-indenyl)zirconium dichloride anddimethyl;

cyclohexylidene-bis(3-isopropyl-indenyl)zirconium dichloride anddimethyl;

methylene-bis[3-(1-methylpropyl)-indenyl]zirconium dichloride anddimethyl;

isopropylidene-bis[3-(1-methylpropyl)-indenyl]zirconium dichloride anddimethyl;

cyclopentylidene-bis[3-(1-methylpropyl)-indenyl]zirconium dichloride anddimethyl;

cyclohexylidene-bis[3-(1-methylpropyl)-indenyl]zirconium dichloride anddimethyl;

methylene-bis[3-(1-methylbutyl)-indenyl]zirconium dichloride anddimethyl;

isopropylidene-bis[3-(1-methylbutyl)-indenyl]zirconium dichloride anddimethyl;

cyclopentylidene-bis[3-(1-methylbutyl)-indenyl]zirconium dichloride anddimethyl;

cyclohexylidene-bis[3-(1-methylbutyl)-indenyl]zirconium dichloride anddimethyl;

methylene-bis[3-(1-phenylethyl)indenyl]zirconium dichloride anddimethyl;

isopropylidene-bis[3-(1-phenylethyl)indenyl]zirconium dichloride anddimethyl;

cyclopentylidene-bis[3-(1-phenylethyl)indenyl]zirconium dichloride anddimethyl;

cyclohexylidene-bis[3-(1-phenylethyl)indenyl]zirconium dichloride anddimethyl;

methylene-bis(3-diphenylmethyl-indenyl)zirconium dichloride anddimethyl;

isopropylidene-bis(3-diphenylmethyl-indenyl)zirconium dichloride anddimethyl;

cyclopentylidene-bis(3-diphenylmethyl-indenyl)zirconium dichloride anddimethyl;

cyclohexylidene-bis(3-diphenylmethyl-indenyl)zirconium dichloride anddimethyl;

methylene-bis[3-(1-cyclohexyl)methylindenyl]zirconium dichloride anddimethyl;

isopropylidene-bis[3-(1-cyclohexyl)methylindenyl]zirconium dichlorideand dimethyl;

cyclopentylidene-bis[3-(1-cyclohexyl)methylindenyl]zirconium dichlorideand dimethyl;

cyclohexylidene-bis[3-(1-cyclohexyl)methylindenyl]zirconium dichlorideand dimethyl;

methylene-bis(3-biscyclohexylmethyl-indenyl)zirconium dichloride anddimethyl;

isopropylidene-bis(3-biscyclohexylmethyl-indenyl)zirconium dichlorideand dimethyl;

cyclopentylidene-bis(3-biscyclohexylmethyl-indenyl)zirconium dichlorideand dimethyl;

cyclohexylidene-bis(3-biscyclohexylmethyl-indenyl)zirconium dichlorideand dimethyl;

methylene-bis(3-biscyclopentylmethyl-indenyl)zirconium dichloride anddimethyl;

isopropylidene-bis(3-biscyclopentylmethyl-indenyl)zirconium dichlorideand dimethyl;

cyclopentylidene-bis(3-biscyclopentylmethyl-indenyl)zirconium dichlorideand dimethyl;

cyclohexylidene-bis(3-biscyclopentylmethyl-indenyl)zirconium dichlorideand dimethyl;

methylene-bis(3-biscyclopropylmethyl-indenyl)zirconium dichloride anddimethyl;

isopropylidene-bis(3-biscyclopropylmethyl-indenyl)zirconium dichlorideand dimethyl;

cyclopentylidene-bis(3-biscyclopropylmethyl-indenyl)zirconium dichlorideand dimethyl;

cyclohexylidene-bis(3-biscyclopropylmethyl-indenyl)zirconium dichlorideand dimethyl;

methylene-bis(3-cyclohexyl-indenyl)zirconium dichloride and dimethyl;

isopropylidene-bis(3-cyclohexyl-indenyl)zirconium dichloride anddimethyl;

cyclopentylidene-bis(3-cyclohexyl-indenyl)zirconium dichloride anddimethyl;

cyclohexylidene-bis(3-cyclohexyl-indenyl)zirconium dichloride anddimethyl;

methylene-bis(3-cyclopentyl-indenyl)zirconium dichloride and dimethyl;

isopropylidene-bis(3-cyclopentyl-indenyl)zirconium dichloride anddimethyl;

cyclopentylidene-bis(3-cyclopentyl-indenyl)zirconium dichloride anddimethyl;

cyclohexylidene-bis(3-cyclopentyl-indenyl)zirconium dichloride anddimethyl;

methylene-bis(3-cyclopropyl-indenyl)zirconium dichloride and dimethyl;

isopropylidene-bis(3-cyclopropyl-indenyl)zirconium dichloride anddimethyl;

cyclopentylidene-bis(3-cyclopropyl-indenyl)zirconium dichloride anddimethyl;

cyclohexylidene-bis(3-cyclopropyl-indenyl)zirconium dichloride anddimethyl;

methylene-bis(3-cycloheptyl-indenyl)zirconium dichloride and dimethyl;

isopropylidene-bis(3-cycloheptyl-indenyl)zirconium dichloride anddimethyl;

cyclopentylidene-bis(3-cycloheptyl-indenyl)zirconium dichloride anddimethyl;

cyclohexylidene-bis(3-cycloheptyl-indenyl)zirconium dichloride anddimethyl;

methylene-bis(3-norbomyl-indenyl)zirconium dichloride and dimethyl;

isopropylidene-bis(3-norbomyl-indenyl)zirconium dichloride and dimethyl;

cyclopentylidene-bis(3-norbomyl-indenyl)zirconium dichloride anddimethyl;

cyclohexylidene-bis(3-norbomyl-indenyl)zirconium dichloride anddimethyl.

Most preferably the metallocene compounds of formula (I) aremethylene-bis(3-isopropyl-indenyl)zirconium dichloride andisopropylidene-bis(3-isopropyl-indenyl)zirconium dichloride.

The preparation of the ligands for the metallocenes of formula (I) canbe carried out by different methods. A particularly suitable method forpreparing the ligands for the metallocenes of formula (I) wherein R⁴ andR⁵ are hydrogen atoms is reported in WO 98/43931. A method for preparingthe ligands for the metallocenes of formula (I) wherein at least one ofthe substituents R⁴ and R⁵ is different from hydrogen atoms is describedin EP-A 0 722 949 and EP-A 0 722 950. The synthetic routes describedtherein, however, are rather complicated and involve the use of thetoxic and expensive dimethoxyethane (DME). Further, since the abovesynthesis requires the use of excessive hydroxides, the disposal of notconsumed hydroxides involves additional environmental protectionmeasures.

According to a further aspect of the present invention, it is provided aprocess for the preparation of a compound of formula (II):

and/or its double bond isomers, wherein R¹, R², R³, R⁴, R⁵, R⁶ and R⁷are defined as above; comprising the following steps:

a) contacting a compound of formula (III):

 and/or its double bound isomer,

wherein R¹, R⁶ and R⁷ have the meaning as described above, with a baseselected from the group consisting of alkali and earth alkali metalhydroxides or alkoxides in the presence of an oxygen containing solvent;

b) treating the obtained corresponding anionic form with a compound ofgeneral formula R⁴R⁵CO, wherein R⁴ and R⁵ have the same meaning asdefined above, in order to obtain a compound of the formula (IV):

 and/or its double bound isomers;

wherein R¹, R⁴, R⁵, R⁶ and R⁷ have the meaning as above mentioned;

c) contacting the compound of formula (IV) with a base, wherein themolar ratio between the base and the compound of formula (IV) is equalto or greater than 2;

d) treating the corresponding di-anionic form of formula (IV) with acompound (V) of formula CHR²R³L, R² and R³ being as defined above and Lis a halogen atom selected from the group 17 of the Periodic Table ofthe Elements (new IUPAC version), wherein the molar ratio between thecompound (V) and the corresponding di-anionic form of formula (IV) isequal to or greater than 2.

The bases, which may be used in step a) are preferably sodium orpotassium hydroxide. The molar ratio between said base and the indenylcompound of formula (III) can vary over a wide range. The process of thepresent invention has the advantage that the base can be used in lessthan stoichiometric amounts. The molar ratio between said base and saidindenyl compound of formula (III) preferably ranges from a catalyticamount to 1. More preferably from 0.01 to 1, and even more preferablyfrom 0.1 to 1.

Preferably, the oxygen containing solvent used in step a) isdimethylsulfoxide (DMSO) or 1-Me-2-pyrrolidinone.

The compound of general formula R⁴R⁵CO, which is used in the above stepa) for introducing the bridge between two indenyl moieties of generalformula (III), can be, for instance, formaldehyde, formaline, acetone,cyclohexanone or cyclopentanone.

The base used in step c) is selected from alkali and earth alkali metalhydroxides, organic lithium compounds and metallic sodium or potassium,preferably the base is buthyllithium.

The contact treatment of compound of general formula (IV) and the base,such as buthyllithium, can be carried out in a solvent such as THF ordiethylether.

In the process according to the present invention L is selected fromchlorine, bromine, iodine and fluorine, preferably L is bromine.Non-limiting examples of compounds of formula CHR²R³L are, for instance,2-bromopropane, 2-bromohexane or diphenylbromomethane. The temperaturein the reaction medium can vary in dependence of the solvent, the natureand the quantity of the used compounds and is generally in the range ofbetween room temperature and reflux temperature of the solvent used.

The purification of the ligand of formula (II) can be carried outaccording to general known methods, such as distillation or filtration.

Non-limiting examples of compounds of formula (II) are:

1,1-bis(3-isopropyl-indenyl)methane;

2,2-bis(3-isopropyl-indenyl)propane;

1,1-bis(3-isopropyl-indenyl)cyclopentane;

1,1-bis(3-isopropyl-indenyl)cyclohexane;

1,1-bis[3-(1-methylpropyl)-indenyl]methane;

2,2-bis[3-(1-methylpropyl)-indenyl]propane;

1,1-bis[3-(1-methylpropyl)-indenyl]cyclopentane;

1,1-bis[3-(1-methylpropyl)-indenyl]cyclohexane;

1,1-bis[3-(1-methylbutyl)-indenyl]methane;

2,2-bis[3-(1-methylbutyl)-indenyl]propane;

1,1-bis[3-(1-methylbutyl)-indenyl]cyclopentane;

1,1-bis[3-(1-methylbutyl)-indenyl]cyclohexane;

1,1-bis[3-(1-phenylethyl)indenyl]methane;

2,2-bis[3-(1-phenylethyl)indenyl]propane;

1,1-bis[3-(1-phenylethyl)indenyl]cyclopentane;

1,1-bis[3-(1-phenylethyl)indenyl]cyclohexane;

1,1-bis(3-diphenylmethyl-indenyl)methane;

2,2-bis(3-diphenylmethyl-indenyl)propane;

1,1-bis(3-diphenylmethyl-indenyl)cyclopentane;

1,1-bis(3-diphenylmethyl-indenyl)cyclohexane;

1,1-bis[3-(1-cyclohexyl)methylindenyl]methane;

2,2-bis[3-(1-cyclohexyl)methylindenyl]propane;

1,1-bis[3-(1-cyclohexyl)methylindenyl]cyclopentane;

1,1-bis[3-(1-cyclohexyl)methylindenyl]cyclohexane;

1,1-bis(3-biscyclohexylmethyl-indenyl)methane;

2,2-bis(3-biscyclohexylmethyl-indenyl)propane;

1,1-bis(3-biscyclohexylmethyl-indenyl)cyclopentane;

1,1-bis(3-biscyclohexylmethyl-indenyl)cyclohexane;

1,1-bis(3-biscyclopentylmethyl-indenyl)methane;

2,2-bis(3-biscyclopentylmethyl-indenyl)propane;

1,1-bis(3-biscyclopentylmethyl-indenyl)cyclopentane;

1,1-bis(3-biscyclopentylmethyl-indenyl)cyclohexane;

1,1-bis(3-biscyclopropylmethyl-indenyl)methane;

2,2-bis(3-biscyclopropylmethyl-indenyl)propane;

1,1-bis(3-biscyclopropylmethyl-indenyl)cyclopentane;

1,1-bis(3-biscyclopropylmethyl-indenyl)cyclohexane;

1,1-bis(3-cyclohexyl-indenyl)methane;

2,2-bis(3-cyclohexyl-indenyl)propane;

1,1-bis(3-cyclohexyl-indenyl)cyclopentane;

1,1-bis(3-cyclohexyl-indenyl)cyclohexane;

1,1-bis(3-cyclopentyl-indenyl)methane;

2,2-bis(3-cyclopentyl-indenyl)propane;

1,2-bis(3-cyclopentyl-indenyl)cyclopentane;

1,1-bis(3-cyclopentyl-indenyl)cyclohexane;

1,1-bis(3-cyclopropyl-indenyl)methane;

2,2-bis(3-cyclopropylindenyl)propane;

1,1-bis(3-cyclopropyl-indenyl)cyclopentane;

1,1-bis(3-cyclopropyl-indenyl)cyclohexane;

1,1-bis(3-cycloheptyl-indenyl)methane;

2,2-bis(3-cycloheptyl-indenyl)propane;

1,1-bis(3-cycloheptyl-indenyl)cyclopentane;

1,1-bis(3-cycloheptyl-indenyl)cyclohexane;

1,1-bis(3-norbomyl-indenyl)methane;

2,2-bis(3-norbomyl-indenyl)propane;

1,1-bis(3-norbomyl-indenyl)cyclopentane;

1,1-bis(3-norbomyl-indenyl)cyclohexane.

Most preferably the compound of formula (II) is2,2-bis(3-isopropyl-indenyl)propane.

The metallocene compounds of formula (I) can be prepared by contactingthe corresponding bis-indenyl ligands of formula (II) with a compoundcapable of forming a delocalized anion on the cyclopentadienyl ring, andwith a compound of formula MX_(p+2), wherein M, X and p are defined asabove.

In the case in which at least one substituent X in the metallocenecompound of the formula (I) which is to be prepared is other than ahalogen, it is necessary to substitute at least one substituent X in themetallocene obtained by at least one substituent X other than a halogen.

The reaction of substituting substituents X by substituents X other thana halogen is carried out using generally applied methods. For example,if the desired substituents X are alkyl groups, the metallocenes can bemade to react with alkylmagnesium halides (Grignard reagents) or withalkyllithium compounds.

In the catalyst used in the process according to the invention, both themetallocene compound of the formula (I) and the alumoxane can be presentas the product of the reaction with an organometallic aluminium compoundof the formula AlR¹¹ ₃ or Al₂R¹¹ ₆, in which the R¹¹ substituents, sameor different, are defined as the substituents R⁸ or are halogen atoms.

The alumoxanes used in the process of the present invention may beobtained by reaction between water and an organometallic compound ofaluminium of formula AlR¹¹ ₃ or Al₂R¹¹ ₆, in which the R¹¹ substituents,same or different, are defined as above, with the condition that atleast one R¹¹ is different from halogen. The molar ratio between thealuminium and water is in the range of 1:1 and 100:1.

Non-limiting examples of aluminium compounds of the formula AlR¹¹ ₃ orAl₂R¹¹ ₆ are: Al(Me)₃, Al(Et)₃, AlH(Et)₂, Al(iBu)₃, AlH(iBu)₂,Al(iHex)₃, Al(iOct)₃, AlH(iOct)₂, Al(C₆H₅)₃, Al(CH₂C₆H₅)₃, Al(CH₂CMe₃)₃,Al(CH₂SiMe₃)₃, Al(Me)₂iBu, Al(Me)₂Et, AlMe(Et)₂, AlMe(iBu)₂, Al(Me)₂iBu,Al(Me)₂Cl, Al(Et)₂Cl, AlEtCl, and Al₂(Et)₃Cl₃, wherein Me=methyl,Et=ethyl, iBu=isobutyl, iHex=isohexyl, iOct=2,4,4-trimethyl-pentyl.

Particularly interesting aluminium compounds are those described in theEuropean application No. 97203332.8 in which the alkyl groups havespecific branched patterns. Non-limiting examples of aluminium compoundsaccording to said European application are:tris(2,3,3-trimethyl-butyl)aluminium, tris(2,3-dimethyl-hexyl)aluminium,tris(2,3-dimethyl-butyl)aluminium, tris(2,3-dimethyl-pentyl)aluminium,tris(2,3-dimethyl-heptyl)aluminium,tris(2-methyl-3-ethyl-pentyl)aluminium,tris(2-methyl-3-ethyl-hexyl)aluminium,tris(2-methyl-3-ethyl-heptyl)aluminium,tris(2-methyl-3-propyl-hexyl)aluminium,tris(2-ethyl-3-methyl-butyl)aluminium,tris(2-ethyl-3-methyl-pentyl)aluminium,tris(2,3-diethyl-pentyl)aluminium,tris(2-propyl-3-methyl-butyl)aluminium,tris(2-isopropyl-3-methyl-butyl)aluminium,tris(2-isobutyl-3-methyl-pentyl)aluminium,tris(2,3,3-trimethyl-pentyl)aluminium,tris(2,3,3-trimethyl-hexyl)aluminium,tris(2-ethyl-3,3-dimethyl-butyl)aluminium,tris(2-ethyl-3,3-dimethyl-pentyl)aluminium,tris(2-isopropyl-3,3-dimethyl-butyl)aluminium,tris(2-trimethylsilyl-propyl)aluminium,tris(2-methyl-3-phenyl-butyl)aluminium,tris(2-ethyl-3-phenyl-butyl)aluminium,tris(2,3-dimethyl-3-phenyl-butyl)aluminium, as well as the correspondingcompounds wherein one of the hydrocarbyl groups is replaced by anhydrogen atom, and those wherein one or two of the hydrocarbyl groupsare replaced by an isobutyl group.

Amongst the above aluminium compounds, trimethylaluminium (TMA),triisobutylaluminium (TIBAL), tris(2,4,4-trimethyl-pentyl)aluminium(TIOA), tris(2,3-dimethylbutyl)aluminum (TDMBA) andtris(2,3,3-trimethylbutyl)aluminum (TTMBA) are preferred.

The alumoxanes used in the catalyst according to the invention areconsidered to be linear, branched or cyclic compounds containing atleast one group of the type:

wherein the substituents R¹² same or different, are C₁-C₂₀-alkyl,C₃-C₂₀-cycloalkyl, C₂-C₂₀-alkenyl, C₆-C₂₀-aryl, C₇-C₂₀-alkylaryl orC₇-C₂₀-arylalkyl radicals, optionally hydrogen atoms, silicon orgermanium atoms, or a —O—Al(R¹²)₂ group and, if appropriate, somesubstituents R¹² can be halogen atoms.

In particular, alumoxanes of the formula:

can be used in the case of linear compounds, wherein n is 0 or aninteger of from 1 to 40 and the substituents R¹² are defined as above,or alumoxanes of the formula:

can be used in the case of cyclic compounds, wherein n is an integer offrom 2 to 40 and the R¹² substituents are defined as above.

The substituents R¹² are preferably ethyl, isobutyl or2,4,4-trimethyl-pentyl groups.

Examples of alumoxanes suitable for use according to the presentinvention are methylalumoxane (MAO), isobutylalumoxane (TIBAO),2,4,4-trimethyl-pentylalumoxane (TIOAO), 2,3-dimethylbutylalumoxane(TDMBAO) and 2,3,3-trimethylbutylalumoxane (TTMBAO).

The catalyst for use in the process according to the invention cansuitably be obtained by a process described in the European applicationNo. 97203331.0 comprising the following steps:

(i) contacting the metallocene compound of the formula (I) with part ofthe described aluminium compound in the absence of water;

(ii) contacting part of the above described aluminium compound withwater in the absence of the metallocene compound of the formula (I) andsuccessively:

(iii) contacting the products obtained in steps (i) and (ii).

The part of aluminium compound used in each one of steps (i) and (ii)can consist of the same compound(s) or different compounds.

The molar ratio between the aluminium and the metal of the metallocenecompound is in general comprised between 10:1 and 20000:1, andpreferably between 100:1 and 5000:1.

Non-limiting examples of compounds able to form an alkylmetallocenecation are compounds of the formula Y⁺Z⁻, wherein Y⁺ is a Brønsted acid,able to donate a proton and to react irreversibly with a substituent Xof the compound of the formula (I), and Z⁻ is a compatible anion whichdoes not coordinate and which is able to stabilize the active catalyticspecies which results from the reaction of the two compounds and whichis sufficiently labile to be displaceable by an olefin substrate.Preferably, the anion Z⁻ consists of one or more boron atoms. Morepreferably, the anion Z⁻ is an anion of the formula BAr₄ ⁽⁻⁾, whereinthe substituents Ar which can be identical or different are arylradicals such as phenyl. pentafluorophenyl orbis(trifluoromethyl)phenyl. Tetrakis-pentafluorophenyl borate isparticularly preferred. Moreover, compounds of the formula BAr₃ canconveniently be used. Compounds of this type are described, for example,in the published International patent application WO 92/00333.

The catalysts of the present invention can also be used on supports.This is achieved by depositing the metallocene compound (A) or theproduct of the reaction thereof with the component (B), or the component(B) and then the metallocene compound (A) on supports such as, forexample, silica, alunina, magnesium halides, styrene/divinylbenzenecopolymers, polyethylene or polypropylene.

A suitable class of supports, which can be used, is constituted byporous organic supports functionalized with groups having activehydrogen atoms. Particularly suitable are those in which the organicsupport is a partially crosslinked styrene polymer. Supports of thistype are described in European application EP-633 272.

Another class of inert supports particularly suitable for use accordingto the invention is that of the olefin, particularly propylene, porousprepolymers described in International application WO 95/26369.

A further suitable class of inert supports for use according to theinvention is that of the porous magnesium halides such as thosedescribed in International application WO 95/32995.

The solid compound thus obtained, in combination with the furtheraddition of the alkylaluminium compound either as such or pre-reactedwith water if necessary, can be usefully employed in the gas-phasepolymerization.

By polymerizing propylene in the presence of the above particularmetallocenes it is possible to obtain in high yields, at temperature ofindustrial interest (i.e. equal to or higher than 40° C.), amorphouspolypropylene having high molecular weights.

The propylene polymerization process according to the invention can becarried out in the liquid phase in the presence or absence of an inerthydrocarbon solvent, or in the gas phase. The hydrocarbon solvent caneither be aromatic such as toluene, or aliphatic such as propane,hexane, heptane, isobutane or cyclohexane.

Although the polymerization temperature and pressure is not critical,the polymerization of propylene is generally carried out at atemperature between 0° C. and 250° C., particularly between 20° C. and150° C., and more particularly between 40° C. and 90° C. Thepolymerization pressure is generally comprised between 0.5 and 100 bar.

The lower the polymerization temperature, the higher are the resultingmolecular weights of the polymers obtained.

The molecular weight of the polymers can be varied merely by changingthe polymerization temperature, the type or the concentration of thecatalytic components or by using molecular weight regulators such ashydrogen.

The polymerization yields depend on the purity of the metallocenecompound of the catalyst. The metallocene compounds obtained by theprocess of the invention can therefore be used as such or can besubjected to purification treatments.

The components of the catalyst can be brought into contact each otherbefore the polymerization. The pre-contact concentrations are generallybetween 1 and 10⁻⁸ mol/l for the metallocene component (A), while theyare generally between 10 and 10⁻⁸ mol/l for the component (B). Thepre-contact is generally effected in the presence of a hydrocarbonsolvent and, if appropriate, of small quantities of monomer. In thepre-contact it is also possible to use a non-polymerizable olefin suchas isobutene and 2-butene.

The propylene polymers obtainable with the process of the presentinvention may have a varying content of isotactic sequences. Generally,the percentage of the isotactic triads (mm) is in the range from 10 to80, preferably from 25 to 50. Therefore, they can be from substantiallyamorphous to partially crystalline. Their melting enthalpy is generallylower than 70 J/g, preferably lower than 50 J/g, and most preferablylower than 20 J/g. Those polymers with the shortest isotactic sequencesshow no detectable melting enthalpy.

The structure of the above polymers of propylene is substantiallyatactic. Nevertheless, it is observed that the isotactic pentads (mmmm)appear to be more numerous than the syndiotactic pentads. Thus, theratio of the isotactic pentads (mmmm) and the syndiotactic pentads(rrrr) satisfy the relation:

(mmmm)/(rrrr)=1.5, and preferably

(mmmm)/(rrrr)=2.0.

The ratio of the pentads (mmmm) and the pentads (mmmr) satisfy therelation:

(mmmm)/(mmmr)=0.8, and preferably

(mmmm)/(mmmr)=0.9, more preferably

(mmmm)/(mmmr)=1.0.

The tacticity of the polymeric chain, i.e. the distribution of therelative configuration of the tertiary carbons, is determined by ¹³C-NMRanalysis.

The molecular weights of the above said propylene polymers can be quitehigh. Thus, the intrinsic viscosity can reach values of greater than 0.5dl/g, even greater than 2 dl/g.

Further, the molecular weights of the propylene polymers are distributedover relatively limited ranges. The molecular weight distribution can berepresented by the ratio M_(w)/Mn which, for the present polymers, isgenerally lower than 4, preferably lower than 3.5 and, more preferably,lower than 3.

The molecular weight distribution can be varied by using mixtures ofdifferent metallocene compounds or by carrying out the polymerization inseveral stages which differ as to the polymerization temperature and/orthe concentrations of the molecular weight regulators.

The structure of the above said propylene polymers appears to be veryregioregular. In fact, according to the ¹³C-NMR, signals relating tosequences (CH₂)_(n) wherein n=2 are not detectable. Generally, less than2% and, preferably, less than 1% of the CH₂ groups are contained insequences (CH₂)_(n) wherein n=2.

The polymers of the invention are generally soluble in common solvents,such as, for instance, chloroform, diethylether, hexane, heptane,toluene and xylene.

The polymers of the invention are endowed with good elastoimericproperties as well as with good optical properties, being quitetransparent.

The polymers of the invention are transformable into shaped articles byconventional material processing, such as moulding, extrusion, injectionetc.

The polymerization reaction according to the invention can be carriedout in the presence of ethylene or of a C₄-C₁₀ alpha-olefin comonomer.It is thus possible to obtain substantially amorphous propylenecopolymers endowed with a good distribution of the comonomer along thepolypropylene chain.

Non-limiting examples of alpha-olefins which can be used as comonomersin the copolymers according to the present invention are ethylene,1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene, 1-decene,1-dodecene, styrene, 1,5-hexadiene and 1,7-octadiene.

The copolymers according to the present invention are characterized by ahomogeneous distribution of the comonomer units within the polymericchain.

A particular interesting embodiment of the present invention isconstituted of a process for preparing copolymers of propylene withethylene.

The analysis of the distribution of the comonomer units in thecopolymers of the invention has been carried out by means of ¹³C-NMRspectroscopy. The assignments were carried out as described by Randallin Macromol. Chem. Phys.1989, 29, 201. The distribution of triads, inthe case of propylene/ethylene, are calculated by the followingrelationship:

PPP=T_(ββ) EPE=T_(δδ) EPP=T_(βδ) PEP=S_(ββ) PEE=S_(βδ)EEE=0.5(S_(δδ)+0.5S_(γδ) )

wherein PEP, EEP and EEE represent the sequencepropylene/ethylene/propylene, ethylene/ethylene/propylene andethylene/ethylene/ethylene, respectively, in the copolymer. For the NMRnomenclature, see J. Carmen, R. A. Harrington, C. E. Wilkes,Macromolecules, 10, 537 (1977). The values are normalised. The higherthe number of isolated ethylene units in the polymeric chain, the morethe values of the ratio PEP/(PEP+EEP+EEE) become closer to the unit.

Table 4 refers to propylene/ethylene copolymers obtained with a processaccording to the present invention.

In particular, in table 4 there are reported the ratiosPEP/(PEP+EEP+EEE) as a function of the weight percentage of ethylene inthe chain for propylene/ethylene copolymers obtained with a processaccording to the present invention, in the presence of the abovereported metallocene compounds. The amounts of ethylene units beingequal, the values of the ratio PEP/(PEP+EEP+EEE) for the copolymers ofthe invention are always higher than those for the copolymers obtainedwith metallocenes used in the comparative examples, reflecting theimproved distribution of ethylene units in the chain.

In particular, the ratio PEP/(PEP+EEP+EEE) satisfies the followingrelationship:

PEP/(PEP+EEP+EEE)≧0.75

preferably:

PEP/(PEP+EEP+EEE)≧0.85

more preferably

PEP/(PEP+EEP+EEE)≧0.9.

The copolymers of the present invention have intrinsic viscosity values(I.V.) generally higher than 0.5 dl/g and preferably higher than 0.6dl/g.

As for the homopolymers, the copolymers of the present invention aregenerally endowed with a narrow molecular weight distribution. The ratioM_(w)/M_(n) for the copolymers of the present invention is generallylower than 4, preferably lower than 3.5 and, more preferably, lower than3.

The glass transition temperatures (Tg) of the copolymers according tothe invention are generally well below 0° C., thus allowing the use ofarticles made thereof to be used at low temperatures.

The propylene polymers of the present invention are particularlysuitable to prepare blends with isotactic polymers of alpha-olefins, inparticular propylene.

Therefore, it is a further aspect of the present invention athermoplastic composition comprising:

(A) 1 to 99% by weight of a propylene polymer optionally containing from0.1 to 20% by moles of units deriving from an olefin of formula CH₂═CHR,R being hydrogen, a C₂-C₂₀-alkyl or a C₆-C₁₂-aryl group, having thefollowing characteristics:

melting enthalpy <70 J/g;

the ratio of the pentads (mmmm)/(rrr)≧1.5; and

the ratio of the pentads (mmmm)/(mmmr)≧0.8;

(B) 1 to 99% by weight of a propylene polymer, optionally containingfrom 0.1 to 20% by moles of units deriving from an olefin of formulaCH₂═CHR, R being hydrogen, a C₂-C₂₀-alkyl or a C₆-C₁₂-aryl group, havingthe following characteristics:

melting enthalpy >70 J/g, and

% of isotactic dyads (m)−% of syndiotactic dyads (r)>0.

In the composition of the present invention the ratio of the quantitiesby weight of the components (A)/(B) is preferably comprised between10:90 and 90:10. More preferably, the ratio of the quantities by weightof the components (A)/(B) is comprised between 30:70 and 70:30.

The structure of the above polymers of propylene used as component (A)is substantially atactic. Nevertheless, it is observed that theisotactic pentads (mmmm) appear to be more numerous than thesyndiotactic pentads. Thus, the ratio of the isotactic pentads (mmmm)and the syndiotactic pentads (rrrr) satisfy the relation:

(mmmm)/(rrrr)=1.5, and preferably

(mmmm)/(rrrr)=2.0.

The ratio of the pentads (mmmm) and the pentads (mmmr) satisfy therelation:

(mmmm)/(mmmr)=0.8, and preferably

(mmmm)/(mmmr)=0.9, more preferably

(mmmm)/(mmmr)=1.0.

The propylene polymers used as component (A) of the compositionaccording to the present invention may have a varying content ofisotactic sequences. Generally, the percentage of the isotactic triads%(mm) is in the range from 10 to 80, preferably from 25 to 50.Therefore, they can be from substantially amorphous to partiallycrystalline and their melting enthalpy is generally lower than 70 J/g,preferably lower than 50 J/g, and most preferably lower than 20 J/g.Those polymers with the shortest isotactic sequences show no detectablemelting enthalpy.

The molecular weights of the above said propylene polymers can be quitehigh. Thus, the intrinsic viscosity is generally greater than 0.5 dl/g,and can reach values greater than 2 dl/g.

Further, the molecular weights of the propylene polymers used ascomponent (A) of the composition according to the present invention aredistributed over relatively limited ranges.

The molecular weight distribution can be represented by the ratioM_(w)/M_(n) which, for the present polymers, is generally lower than 4,preferably lower than 3.5 and, more preferably, lower than 3.

The structure of the above said propylene polymers, which is used ascomponent (A) of the composition according to the present invention,appears to be very regioregular. In fact, according to the ¹³C-NMR,signals relating to sequences (CH₂)_(n) wherein n=2 are not detectable.Generally, less than 2% and, preferably, less than 1% of the CH₂ groupsare contained in sequences (CH₂)_(n) wherein n=2.

The melting point of the isotactic polypropylene used as component (B)is generally between 110° C. and 160° C., and can even reach valuesabove 160° C.

The molecular weight of the substantially isotactic polypropylene can bequite high. Thus, the intrinsic viscosity can reach values of greaterthan 1 dl/g, even greater than 2 dl/g. Preferably, the melting enthalpyof the isotactic polymer of propylene is >90 J/g.

Examples of isotactic polymers of propylene for use as component (B) arecommercial available isotactic polypropylene, which are produced bymeans of conventional titanium or vanadium based heterogenesZiegler-Natta-type catalysts. Also can be used metallocene basedisotactic polymers having the above described characteristics. Polymersmade by means of metallocenes generally have narrow molecular weightdistribution M_(w)/M_(n), such as values of lower than 3.

In the above mentioned copolymers, which can be used under (A) and/or(B), the co-monomer can for instance, without any limitation, selectedfrom ethylene, 1-butene, styrene, or cyclohexene.

The melting point of the isotactic propylene copolymers used under (B)is generally between 110° C. and 140° C. The fraction soluble in xyleneat 25° C. is generally less than 10%.

The composition of the present invention may contain, as necessary,various additives, reinforcing agents and fillers, such as heatstabilizers, antioxidants, light stabilizers, antistatic agents,lubricants, nucleating agents, flame retardants, pigments or dyes, glassfiber, carbon fiber, calcium carbonate, calcium sulfate, barium sulfate,magnesium hydroxide, mica, talc, or clay.

The preparation of the present composition comprising the components (A)and (B) is not critical and can be carried out by a method commonly usedin the preparation of conventional polypropylene compositions, whereinmelt kneading is conducted with heating, using, for example, a kneader(e.g. kneader, Banbury, rolls) or a single-screw or twin-screw extruder.

The composition of the present invention can be processed in the samemanner as conventional polypropylene compositions. They can be extruded,injection moulded, compression moulded, in order to obtain films,fibers, filaments sheets, fabric, wire and cable coatings. For instance,the composition according to the present invention can also be used forthe preparation of low-temperature-heat-sealing film.

Article, in particular films and sheets made of the compositionsaccording to the present invention have excellent transparency. Afurther advantage of the compositions of the present invention is theresistance to blooming. Blooming can be a severe problem in softpolymeric compositions because it causes surface stickiness.

The miscibility of the composition of the components (A) and (B) of thepresent invention was evaluated by haze measurments (ASTM D1003) andTransmission Electron Micrograph (TEM) microstructures.

BRIEF DESCRIPTION OF THE FIGURES

The enhanced miscibility of the substantially amorphous polymer ofpropylene with isotactic polypropylene is illustrated by means of thefollowing FIGS. 1 and 2, which are Transmission Electron Micrographs(TEM).

FIG. 1 is a TEM (45000×) of a composition according to the presentinvention as described in Example 14, comprising a substantiallyamorphous polypropylene made by rac-Me₂C(3-iPr-Ind)₂ZrCl₂ and acommercial substantial isotactic polypropylene, Moplen Q30P (I.V.:2.6dl/g) (50/50 wt. %). The microstructure shows that the compositionaccording to the present invention is substantially homogeneous.

FIG. 2 is a TEM (45000×) of a composition of amorphous polypropylenemade by Me₂Si(9-Flu)₂ZrCl, and commercial substantial isotacticpolypropylene, Moplen Q30P (50/50 wt. %) as described in ComparisonExample 15. The dark and bright areas of the picture show the existenceof substantially two phases, i.e the components (A) and (B) are lessmiscible.

The following examples are given for illustrative purposes and are notintended to limit the scope and spirit of the invention.

GENERAL PROCEDURES AND CHARACTERIZATIONS

The following abbreviations are used:

THF=tetrahydrofuran

Et₂O=ethyl ether

NaOEt sodium ethoxide

^(t)BuOK potassium tert-butoxide

DMSO=dimethyl sulfoxide

DMF=N,N-dimethylformamide

BuLi=butyllithium

All operations were performed under nitrogen by using conventionalSchlenk-line techniques. Solvents were distilled from blueNa-benzophenone ketyl (Et₂O), CaH₂ (CH₂Cl₂), or AliBu₃ (hydrocarbons),and stored under nitrogen. BuLi (Aldrich) was used as received.

The ¹H-NMR analyses of the metallocenes were carried out on a DPX 200Bruker spectrometer (CD₂Cl₂, referenced against the middle peak of thetriplet of residual CHDCl₂ at 5.35 ppm). All NMR solvents were driedover P205 and distilled before use. Preparation of the samples wascarried out under nitrogen using standard inert atmosphere techniques.

The ¹³C-NMR and ¹H-NMR analyses of the polymers were carried out on aBruker DPX 400 spectrometer operating at 400.13 MHz and 100.61 MHzrespectively. The samples were analyzed as solutions intetrachlorodideuteroethane at 120° C.

The intrinsic viscosity (I.V.) was measured in tetralin at 135° C.

The melting points of the polymers (Tm) were measured by DifferentialScanning Calorimetry (D.S.C.) on an instrument DSC Mettler, according tothe following method. About 10 mg of sample obtained from thepolymerization were cooled to −25° C. and thereafter heated at 200° C.with a scanning speed corresponding to 20° C. minute. The sample waskept at 200° C. for 5 minutes and thereafter cooled to 0° C. with ascanning speed corresponding to 20° C./minute. Then, a second scanningwas carried out with a scanning speed corresponding to 110° C./min. Thevalues reported are those obtained in the second scanning.

The distribution of molecular weights was determined by GPC carried outon an instrument WATERS 150 in orthodichlorobenzene at 135° C.

PREPARATION OF THE METALLOCENES

The synthesis of rac-isopropylidene-bis(3-isopropyl-indenyl)zirconiumdichloride (rac-CMe₂(3-iPr-Ind)₂ZrCl₂),rac-isopropylidene-bis(3-methyl-indenyl)zirconium dichloride(rac-CMe₂(3-Me-Ind)₂ZrCl₂),rac-isopropylidene-bis(3-ter-butyl-indenyl)zirconium dichloride(rac-CMe₂(3-tBu-Ind)₂ZrCl₂) were carried out as described in WO96/22995. The synthesis ofrac-dimethylsilandiyl-bis(9-fluorenyl)zirconium dichloride(rac-SiMe₂(9-fluorenyl)₂ZrCl₂) was carried out as described in EP-A-0632 066. The 1:6 rac/meso mixture ofdimethylsilanediyl-bis(2-methyl-4-phenyl-indenyl)zirconium dichlorideSiMe₂(2-methyl-4-phenyl-indenyl)₂ zirconium dichloride was purchasedfrom Boulder Scientific.

Synthesis of 2,2-bis(1-iso-Propyl-3-indenyl)propane

Synthesis of 2,2-bis(3-Indenyl)propane

Indene (Aldrich, 89.5% by G.C.) was purified by percolation overactivated alumina. DMSO (Aldrich, 99%), acetone (99%), KOH and NaOH(Carlo Erba) were used as received.

Synthesis with KOH at Low Temperature

136.8 g of indene (1.054 moli), 1 L of DMSO and 12.5 g of powdery KOH(85%, 189 mmol) were charged under nitrogen in a 1.5 L jacketed reactorequipped with thermometer and magnetic stirring bar. KOH/Indene=0.18.

The dark brown mixture was stirred 15 min at room temperature and thencooled to 12-15° C. Acetone (35 ml, 477 mmol) was added over 30 min withstirring. Acetone/indene=0.45.

At the end of the addition, the mixture was stirred at room temperaturefor 16 h, to give a dark green slightly viscous solution. This solutionwas poured onto ice containing NH₄Cl, then the precipitate was filteredand washed with copious water, then with 1.2 L of cold MeOH. The ochrapowdery product was dried in vacuo. 103.7 g of 2,2-bis(3-indenyl)propane(purity 93.3% by G.C.) were obtained. The title product wascharacterized by means of ¹H NMR.

Synthesis with Catalytic Amount of KOH

10 g of indene (77 mmol), 80 mL of DMSO and 1 pellet (0.25 g) of KOH(3.8 mmol) were charged under nitrogen in a 250 mL flask equipped withthermometer and magnetic stirring bar. KOH/indene=0.049.

The dark brown mixture was stirred 15 min at 50° C. Acetone (2.56 ml, 35mmol) was added over 5 min with stirring. Acetone/indene 0.45.

At the end of the addition, the mixture was kept at 50° C. for 6.5 h,the dark green slightly viscous solution was allowed to cool to roomtemperature and poured onto ice (no NH₄Cl added), and a milky suspensionis obtained. The precipitate was filtered, the filtrate remain milky,and the rate of filtration is somewhat slower than when NH₄Cl is added.Addition of NH₄Cl causes separation of more organic product and thewater layer becomes more clear (faster filtration rate). The residue waswashed with copious water, then with 200 mL of MeOH (at roomtemperature). The ochra powdery product was dried in vacuo. 6.3 g of2,2-bis(3-indenyl)propane were obtained (purity 98.8%, isolated yieldbased on acetone 65.6%).

Synthesis of 2,2-bis(1-iso-Propyl-3-indenyl)propane.

4.5 g of 2,2-bis(3-indenyl)propane (purity 94%, 15.53 mmol) weredissolved in 50 mL of anhydrous Et₂O in a 250 mL Schlenk, then cooled to0° C., 14 mL of 2.5 M BuLi in hexane (35 mmol) were added in 10 min withstirring, then the mixture was allowed to reach room temperature andthen stirred for 5 h. After 2 h, a yellow precipitate starts forming.3.88 mL of iso-propylbromide (41.32 mmol) and 5 mL of Et₂O were addedunder nitrogen: the yellow precipitate remains. The mixture was stirredfor 16 h at room temperature. At the end the so obtained brownsuspension was analyzed by G.C.: Low boiling impurities 3.9%,2,2-bis(3-indenyl)propane 38.3%, medium boiling impurities 1.3%,monoisopropyl derivative 16.4%, product (two isomers) 32.8%, highboiling impurities 7.3%. To the mixture was added additional 11.64 mL of2-Br-propane (124 mmol) and then refluxed for 7 hours. In 2 hours themixture turns orange and the suspension gradually dissolves. At the endthe solution was cooled and treated with water, the layers wereseparated, the water layer was extracted twice with Et₂O, the organiclayers were combined and dried over Na₂SO₄, filtered, concentrated invacuo to yield 5.38 g of orange oil which was analyzed by G.C.: Lowboiling impurities 3.9%, 2,2-bis(3-indenyl)propane 0.5%, medium boilingimpurities 1.4%, monoisopropyl derivative 6.0%, product (two isomers)82.5%, high boiling impurities 5.7%. (yield 80% based on the G.C.analysis). The title product was characterized by means of ¹H NMR.

Synthesis of rac-Methylene-bis(3-t-butyl-1-indenyl)zirconium Dichloride

a. Synthesis of 3-t-Butyl-1-indene

42.0 g of indene (technical grade, 94% by GC, 39.5 g, 340 mmol), 50%wt.aqueous KOH (308 g in 308 mL) and 15.8 g of Adogen (Aldrich, 34 mmol),dissolved in 139.7 g of tert-butylbromide (1019.6 mmol), were introducedin this order, at room temperature, in a 1 L jacketed glass reactor withmechanical stirrer (Büichi). The organic phase turned green. The mixturewas heated to 60° C., maintained under vigorous stirring for two hours(a pressure build-up to 2.5 bar-g was observed) and then cooled to roomtemperature. The total reaction time was 3 hours. The organic phase wasextracted with technical hexane (3×200 mL) and analyzed by GC,demonstrating a conversion of 74.5%wt. of 3-tert-butyl-indene and of1.8%wt. of 1-tert-butyl-indene, the unreacted indene being equal to13.7%wt. The solution was evaporated under reduced pressure (rotovac)and the resulting dark brown viscous liquid was distilled at 1 mmHg,collecting the fraction boiling between 70 and 80° C. (40 g, 76.8% of3-tert-butyl-indene and 19.5% of 1-tert-butyl-indene, no indene).

b. Synthesis of bis(1-t-Butyl-3-indenyl)methane

In a three neck, 1 L flask with stirring bar were introduced in thisorder: 10.32 g of ^(t)BuOK (92 mmol), 400 mL of DMF, 80.6 g oftert-butyl-indene (98.2% by GC, 460 mmol), obtained as described above,and 18.6 mL of aqueous formalin (37%, 6.9 g, 230 mmol); said reactantswere added dropwise over 15 minutes. A mildly exothermic reaction wasobserved and the solution turned red. The mixture was stirred at roomtemperature for 2 hours; then the reaction was quenched by pouring themixture on ice and NH₄Cl, extracted with Et₂O (2×250 mL) andconcentrated under reduced pressure, thus yielding an orange oilyproduct having the following G.C. composition: 1-^(t)BuInd, 0.3%;3-^(t)BuInd, 2.8%; bis(1-t-butyl3-indenyl)methane, 78.3%; the rest beingbyproducts.

The yield of the raw product was 83.6 g, corresponding to a yield of79.9% The orange oily product crystallized upon standing (about 1 hour).The obtained product was further purified by washing with pentane, thusisolating bis(3-tert-butyl-1-indenyl)methane as a light yellow powder,99.8% pure by G.C.

c. Synthesis of Methylene-bis(3-t-Butyl-1-indenyl)zirconium Dichloride

11.0 g of pure bis(1-tert-butyl-3-indenyl)methane (30.9 mmol), obtainedas described above, were dissolved in 200 mL Et₂O, in a 250 mL Schlenktube, and the solution was cooled to −15° C. 40 mL of 1.6 M BuLi inhexane (63.3 mmol) were added dropwise, over 15 minutes, under stirring.The solution was allowed to warn to room temperature and stirred for 4.5hours. An increasing turbidity developed with final formation of ayellow suspension. 7.2 g of ZrCl₄ (30.9 mmol) were slurried in 200 mLpentane. The two mixtures were both cooled to −80° C. and the Li saltsolution in Et₂O was quickly added to the ZrCl₄ slurry in pentane. Thecooling bath was removed and after 20 minutes the color of the slurrychanged from yellow to red. The reaction mixture was stirred overnightat room temperature and then was brought to dryness under reducedpressure. The red powder was slurried in 200 mL of pentane andtransferred into a filtration apparatus equipped with side arm (to allowsolvent refluxing) connecting the system above and below the frit, areceiving flask on the bottom and bubble condenser on the top. The redsolid was extracted with refluxing pentane for about 3.5 hours. Thefiltrate was evaporated to dryness under reduced pressure to give a redpaste which contained rac-CH₂(3-^(t)Bu-1-Ind)₂ZrCl₂ free from its mesoisomer, but containing polymeric byproducts. The paste was washed twicewith Et₂O (20+10 mL) to give 1 g of pure product. The red solid on thefrit was further extracted with CH₂Cl₂ until the filtrate was lightorange (6 hours) and dried. ¹H-NMR analysis showed the presence of purerac-CH₂(3-^(t)Bu-Ind)₂ZrCl₂ (7.25 g). The total yield (8.25 g of redpowder) of rac-CH₂(3-^(t)Bu-Ind)₂ZrCl₂ was 52%.

¹H NMR (CDCl₃, δ, ppm): s, 1.41, ^(t)Bu, 18H; s, 4.78, CH₂, 2H; s, 5.79,2H, Cp-H; m, 7.15, 2H, m, 7.36, 2H; m, 7.47, 2H; m, 7.78, 2H.

Synthesis of Methylene-bis(3-iso-Propyl-1-indenyl)ZrCl₂

a. Synthesis of 3-iso-Propyl-1-indene

25 g of indene (Aldrich, 94.4%) in 140 mL Et₂O were placed in a 0.5 Lflask and cooled to −20° C.; 141 mL of n-BuLi (1.6 M in hexane, 226mmol) were added dropwise in about 30′. The reaction mixture was allowedto warm to room temperature and then stirred for 5 hours (brown-orangesolution). This solution was then slowly added to a solution of 101 mLof i-PrBr (Aldrich, MW 123 g/mol, d=1.31 g/mL, 1.07 mol) in 140 mL Et₂Omaintained at 0° C. The reaction was allowed to proceed with stirring atroom temperature for 72 hours. The mixture was poured onto 300 g of ice,the water layer was extracted with Et₂O (3×200 mL) and the Et₂O washcombined with the organic layer, dried over MgSO₄ and after filtrationthe solvent was removed under vacuum to leave 30.9 g of a yellow oil(yield based on GC analysis is 62%). 18 g of this oil was distilled(adding NaOH pellets to avoid polymerization, with a 20 cm vigreuxcolumn) collecting the fraction boiling at 95-105° C. at 10 mmHg, 10 g,GC: i-PrInd (2 isomers)=92.1%, ¹H NMR (CDCl₃, d, ppm): d, 1.45, 1.47,6H; m, 3.47, CH, 1H; s, 3.47, 2H, CH₂; s, 6.35, 1H; m, 7.47, 2H; m,7.3-7.7, 4H. Major isomer is 3-i-Pr-indene.

b. Synthesis of bis(iso-Propyl-indenyl)methane

In a three neck, 500 mL flask with stirring bar were introduced in thisorder: 10 g of i-Pr-indene (92%, MW 158, 58.3 mmol) dissolved in 250 mLof DMSO, and 1.42 g of t-BuOK (MW 112.82. 12.6 mmol). The yellowsolution turns green. 2.56 mL of aqueous formalin (37%, MW 30.03, 31.6mmol) in 70 mL of DMSO were added in 15′. A mildly hexothermic reactionis observed and the solution turns dark brown. At the end of theaddition the reaction mixture was stirred for 16 h at room temperature.

The reaction was quenched by pouring the mixture on 200 g ice with 0.3 gNH₄Cl. The organic product was extracted with Et₂O, the water layer waswashed with Et₂O (3×100 mL), the organic layers combined, dried overMgSO₄, filtered and concentrated to leave 13.65 g of yellow oil, whichcontains 32% of the desired product by GC analysis.

c. Synthesis of Methylenebis(3-iso-Propyl-indenyl)ZrCl₂

13.6 g of raw bis(3-iso-propyl-1-indenyl)methane were dissolved in 200mL Et₂O in a 250 mL Schlenk tube, and the solution cooled to −80° C.33.3 mL of 2.5 M BuLi in hexane (83.2 mmol) were added dropwise over 15min with stirring. The solution is allowed to warm to room temperatureand stirred for 5 hours. An increasing turbidity develops with finalformation of an orange precipitate. Et₂O was removed under vacuum and200 mL of toluene were added. 9.7 g of ZrCl₄ (MW 233.03, 41.62 mmol)were slurried in 200 mL of toluene. The two mixtures were both cooled to−80° C. and the ZrCl₄ slurry in toluene was quickly added to the Li saltsolution in toluene. The cooling bath is removed. The reaction mixtureis stirred overnight at room temperature. Filtration: the residue was asticky glue (eliminated). The filtrate was evaporated to 25 mL underreduced pressure: the solid precipitated was isolated by filtration. Thetitle compound was characterized by ¹H NMR.

POLYMERIZATION

Methylalumoxane (MAO)

A commercial (Witco) 10% toluene solution was dried in vacuo until asolid, glassy material was obtained which was finely crushed and furthertreated in vacuo until all volatiles were removed (4-6 hours, 0.1 mmHg,50° C.) to leave a white, free-flowing powder.

Preparation of the Cocatalyst

The catalyst mixture was prepared by dissolving the desired amount ofthe metallocene with the proper amount of the MAO solution, obtaining ared solution, which was stirred for 10 min at ambient temperature andthen injected into the autoclave at the polymerization temperature inthe presence of the monomer.

Propylene Homopolymerization

EXAMPLES 1-6 AND COMPARATIVE EXAMPLES 8-10

Propylene was charged at room temperature in a 1-L jacketedstainless-steel autoclave, equipped with magnetically driven stirrer anda 35-mL stainless-steel vial, connected to a thermostat for temperaturecontrol, previously purified by washing with a TIBA solution in hexaneand dried at 50° C. in a stream of propylene. AliBu₃ (1 mmol in hexane)was added as scavenger before the monomer. The autoclave was thenthermostated at 2° C. below the polymerization temperature, and then thetoluene solution containing the catalyst/cocatalyst mixture was injectedin the autoclave by means of nitrogen pressure through thestainless-steel vial, the temperature rapidly raised to thepolymerization temperature and the polymerization carried out atconstant temperature for 1 hour. After venting the unreacted monomer andcooling the reactor to room temperature, the polymer was dried underreduced pressure at 60° C.

The polymerization conditions are reported in Table 1.

The characterisation data of the obtained polymers are shown in table 2.

EXAMPLE 7

The polymerization was carried out as above described, except that a 4 Lautoclave was used and the polymerization time was 2 hours.

The polymerization conditions are reported in Table 1.

The characterisation data of the obtained polymer are shown in table 2.

Propylene/Ethylene Copolymerization

EXAMPLES 11-13

The copolymerizations were carried out in a 2.6 L jacketedstainless-steel autoclave as described above. AliBu₃ (1 mmol in hexane)and propylene (530 g, 1 L total volume at 60° C.) were charged andthermostatted at 55° C., the catalyst/cocatalyst mixture was injected inthe autoclave by means of ethylene pressure (using the amount ofethylene required to achieve the bath composition shown in Table 5)through the stainless-steel vial. the temperature rapidly raised to 60°C. and the polymerization carried out at constant temperature andmonomer composition, by feeding a mixture of ethylene and propylene 5/95by weight (Examples 9 and 10) or 3/97 by weight (Example 11). Thepolymerizations were stopped with CO, the not consumed monomers vented,and the polymer dried under reduced pressure at 60° C.

The polymerization conditions are reported in Table 3.

The characterisation data of the obtained copolymers are shown in table4.

PREPARATION OF THE COMPOSITIONS EXAMPLE 14

20 g of a propylene polymer obtained according to Example 3 [component(A)], the same amount of Moplen Q30P (a commercial isotacticpolypropylene made by Montell) [component (B)], and 0.1 wt % of IRGANOXB215 (a commercial stabilizer provided by the Ciba company) were mixedin a Banbury at 200° C. for 10 min at 50 rpm. The blend obtained thereofwas compression moulded into plaques of 1 mm thickness at 200° C. for 5min and subsequently cooled in a water cooled press. The characteristicof the obtained composition is illustrated in Table 5.

EXAMPLE 15 (COMPARISON)

The example was carried out according to example 14, with the exceptionthat a polypropylene obtained with SiMe₂(9-fluorenyl)₂ZrCl₂ was used ascomponent (A). The characteristic of the obtained composition isillustrated in Table 5.

The beneficial characteristic of the composition according to thepresent invention is illustrated in Table 5 by the inferior haze valueof the composition according to Example 14 with regard to thecomposition according to the comparison example 15.

EXAMPLE 16 (COMPARISON)

A propylene polymerization was carried out according to the proceduredescribed in examples 1-6 but using 0.5 mg of a 1:6 rac/meso mixture ofSiMe₂(2-methyl4-phenyl-indenyl)₂ZrCl₂ in the presence of 100 ml H₂. Thepolymerization conditions are reported in Table 1. The characteristic ofthe obtained composition is illustrated in Table 5.

TABLE 1 zirconocene dichloride Al/Zr Tp yield activity Example type mg(mol) (° C.) (g) (Kg/g_(cat) · h) 1 CMe₂(3-iPr-Ind)₂ 3 1000 20 33 10.8 2″ 2 1000 30 68 33.9 3 ″ 2 1000 45 74 36.9 4 ″ 1 1000 50 36 35.8 5 ″ 11000 60 62 61.9 6 CH₂(3-iPr-Ind)₂ 0.8 1000 50 42 52 7 ″ 5 3000 40 830 838 (comp) CMe₂(3-Me-Ind)₂ 1 1000 50 10 10 9 (comp) CMe₂(3-tBu-Ind)₂ 0.55000 50 37.6 75.3 10 (comp) CH₂(3-tBu-Ind)₂ 2.0 1000 50 144.7 72.3 16(comp) SiMe₂(2-methyl- 0.5 1000 60 49.38 n.d. 4-phenyl- indenyl)₂

TABLE 2 zirconocene Exp. Triad Distribution % I.V Tg Example dichloridemm rm rr dl/g ° C. 1 CMe₂(3-iPr-Ind)₂ 36.7 39.4 23.9 2.24 −0.3 2 ″ 35.639.6 24.8 2.27 1.0 3 ″ 33.9 40.9 25.2 1.55 n.d. 4 ″ 32.2 40.5 27.3 1.54n.d. 5 ″ 30.3 42.7 27.0 0.87 n.d. 6 CH₂(3-iPr-Ind)₂ 52.9 30.5 16.6 0.9n.d. 7 ″ 55.5 28.4 16.1 1.17 −9 8 (comp) CMe₂(3-Me-Ind)₂ n.d. n.d. n.d.oil n.d. 9 (comp) CMe₂(3-tBu-Ind)₂ 96.8 2.1 1.1 0.89 n.d 10 (comp)CH₂(3-tBu-Ind)₂ 98.2 1.2 0.6 1.59 n.d n.d. not determined

TABLE 3 liquid phase activity Exam- zirconocene dichloride Al/Zrethylene Tp yield (Kg/ ple type mg (mol) % wt (° C.) (g) g_(cat) · h) 11CMe₂(3-iPr-Ind)₂ 2 1000 0.82 60 94 94 12 ″ 2 1000 0.4 60 126 126 13 ″ 21000 0.2 60 55 55

TABLE 4 N. M. R. liquid phase PEP/ zirconocene ethylene ethylene (%mols) (PEP + EEP + I.V. Tg Ex. dichloride % wt (% wt) PEP EEE EEP EEE)(dl/g) (° C.) 11 CMe₂(3-iPr-Ind)₂ 0.82 13.8 0.171 0 0.022 0.89 0.60−19.8 12 ″ 0.4 7.7 0.104 0 0.007 0.94 0.67 −13.5 13 ″ 0.2 9.9 0.130 00.011 0.91 0.63 −15.8

TABLE 5 I.V. (dl/g) ¹³C-NMR of component (A) I.V. (dl/g) Component(A)/(B) Pentads mmmm/r mmmm/ Haze Example zirconocene Component (A) (B)(wt/wt) mmmm mmmr rrrr rrr mmmr (%) 14 CMe₂(3-iPr-Ind)₂ 1.55 2.6 50/5014.80 14.24 6.41 2.31 1.04 61 15 (comp) SiMe₂(9-Flu)₂ 1.49 2.6 50/50 7616 (comp) SiMe₂(2-methyl-4- 1.05 6.8 40/60 10.25 16.47 2.79 3.67 0.62phenyl-indenyl)₂

What is claimed is:
 1. A process for the preparation of polymers ofalpha-olefins, comprising the polymerization reaction of at least onealpha-olefin containing from 3 to 20 carbon atoms in the presence of acatalyst obtained by contacting: (A) a metallocene compound in theracemic form of the formula (I):

 wherein substituents R¹ are hydrogen atoms; R² and R³ are,independently from each other, C₁-C₂₀-alkyl, C₃-C₂₀-cycloalkyl,C₂-C₂₀-alkenyl, C₆-C₂₀-aryl, C₇-C₂₀-alkylaryl or C₇-C₂₀-arylalkylradicals, optionally containing silicon or germanium atoms; or where R²and R³ can be joined together to form a 4 to 6 membered ring or a 6 to20 fused ring system; R⁴ and R⁵, same or different, are hydrogen atomsor —CHR⁸R⁹ groups; R⁴ and R⁵ can form a ring having 3 to 8 carbon atomswhich can contain hetero atoms; the R⁸ and R⁹ substituents, same ordifferent, are hydrogen atoms, C₁-C₂₀-alkyl, C₃-C₂₀-cycloalkyl,C₂-C₂₀-alkenyl, C₆-C₂₀-aryl, C₇-C₂₀-alkylaryl or C₇-C₂₀-arylalkylradicals, which can form a ring having 3 to 8 carbon atoms which cancontain hetero atoms; the R⁶ and R⁷ substituents, same or different, arehydrogen, C₁-C₂₀-alkyl, C₃-C₂₀-cycloalkyl, C₂-C₂₀-alkenyl, C₆-C₂₀-aryl,C₇-C₂₀-alkylaryl or C₇-C₂₀-arylalkyl radicals, optionally containingsilicon or germanium atoms; and optionally two adjacent R⁶ and R⁷substituents can form a ring comprising from 5 to 8 carbon atoms; M is atransition metal selected from those belonging to group 3, 4, 5, 6 or tothe lanthanide or actinide groups in the Periodic Table of the Elements(new IUPAC version), X, same or different, is a monoanionic ligand, suchas a hydrogen atom, a halogen atom, an R¹⁰, OR¹⁰, OSO₂CF₃, OCOR¹⁰, SR¹⁰,NR¹⁰ ₂ or PR¹⁰ ₂ group, wherein the substituents R¹⁰ are a C₁-C₂₀-alkyl,C₃-C₂₀-cycloalkyl, C₂-C₂₀-alkenyl, C₆-C₂₀-aryl, C₇-C₂₀-alkylaryl orC₇-C₂₀-arylalkyl radical, optionally containing silicon or germaniumatoms; p is an integer from 0 to 3, p being equal to the oxidation stateof the metal M minus two; and (B) at least one of an alumoxane and acompound capable of forming an alkyl metallocene cation; wherein thepolymers of alpha-olefins are amorphous.
 2. The process according toclaim 1, wherein said alpha-olefin is propylene.
 3. The processaccording to claim 1, wherein in the metallocene compound of formula (I)the transition metal M is selected from titanium, zirconium or hafnium.4. The process according to claim 1, wherein in the metallocene compoundof formula (I) the transition metal M is zirconium.
 5. The processaccording to claim 1, wherein in the metallocene compound of formula (I)the X substituents are chlorine atoms or methyl groups.
 6. The processaccording to claim 1, wherein in the metallocene compound of formula (I)the substituents R⁶ and R⁷ are hydrogen atoms.
 7. The process accordingto claim 1, wherein the metallocene compound of formula (I) ismethylene-bis(3-isopropylindenyl)zirconium dichloride orisopropylidene-bis(3-isopropyl-indenyl)zirconium dichloride.
 8. Theprocess according to claim 1, wherein said alumoxane is obtained byreacting water with an organo-aluminium compound of formula AlR¹¹ ₃ orAl₂R¹¹ ₆, wherein the R¹¹ substituents, same or different, are definedas the substituents R⁸, or are halogen atoms, and at least one R¹¹ isnot a halogen.r ratio between the aluminium and water is in the range of1:1 and 100:1.
 9. The process according to claim 8, wherein the molarratio between the aluminium and water is in the range of 1:1 and 100:1.10. The process according to claim 1, wherein said alumoxane ismethylalumoxane (MAO), isobutylalumoxane (TIBAO),2,4,4-trimethyl-pentylalumoxane (TIOAO), 2,3-dimethylbutylalumoxane(TDMBAO) or 2,3,3-trimethylbutylalumoxane (TTMBAO).
 11. The processaccording to claim 8, wherein the molar ratio between the aluminium andthe metal of the metallocene compound is comprised between 100:1 and5000:1.
 12. The process according to claim 1, wherein the compoundcapable of forming a metallocene alkyl cation is a compound of formulaY⁺Z⁻, wherein Y⁺ is a Bronsted acid, able to give a proton and to reactirreversibly with a substituent X of the metallocene of formula (I) andZ⁻ is a compatible anion, which does not coordinate, which is able tostabilize the active catalytic species originating from the reaction ofthe two compounds, and which is sufficiently labile to be able to beremoved from an olefinic substrate.
 13. The process according to claim12, wherein the compound of formula Y⁺Z⁻ istetrakis-pentafluorophenylborate.
 14. The process according to claim 1,wherein said process is carried out at a temperature comprised between 0and 250° C. and at a pressure comprised between 0.5 and 100 bar.
 15. Theprocess according to claim 1, wherein the process is carried out in thepresence of ethylene or of a C₄-C₁₀ alpha-olefin comonomer.
 16. Athermoplastic composition comprising: (A) 1 to 99% by weight of apropylene polymer optionally containing from 0.1 to 20% by moles ofunits deriving from an olefin of formula CH₂═CHR, R being hydrogen, aC₂-C₂₀-alkyl or a C₆-C₁₂-aryl group, having the followingcharacteristics: melting enthalpy <70 J/g; the ratio of the pentads(mmmm)/(rrrr)≧1.5; and the ratio of the pentads (mmmm)/(mmmr)≧0.8; (B) 1to 99% by weight of a propylene polymer, optionally containing from 0.1to 20% by moles of units deriving from an olefin of formula CH₂═CHR, Rbeing hydrogen, a C₂-C₂₀-alkyl or a C₆-C₁₂-aryl group, having thefollowing characteristics: melting enthalpy >70 J/g, and % of isotacticdyads (m)−% of syndiotactic dyads (r)>0; wherein component (A) isproduced from a process comprising the polymerization reaction of atleast one alpha-olefin containing from 3 to 20 carbon atoms in thepresence of a catalyst obtained by contacting: (A1) a metallocenecompound in the racemic form of the formula (I):

 wherein substituents R¹ are hydrogen atoms; R² and R³ are,independently from each other, C₁-C₂₀-alkyl, C₃-C₂₀-cycloalkyl,C₂-C₂₀-alkenyl, C₆-C₂₀-aryl, C₇-C₂₀-alkylaryl or C₇-C₂₀-arylalkylradicals, optionally containing silicon or germanium atoms; or where R²and R³ can be joined together to form a 4 to 6 membered ring or a 6 to20 fused ring system; R⁴ and R⁵, same or different, are hydrogen atomsor —CHR⁸R⁹ groups; R⁴ and R⁵ can form a ring having 3 to 8 carbon atomswhich can contain hetero atoms; the R⁸ and R⁹ substituents, same ordifferent, are hydrogen atoms, C₁-C₂₀-alkyl, C₃-C₂₀-cycloalkyl,C₂-C₂₀-alkenyl, C₆-C₂₀-aryl, C₇-C₂₀-alkylaryl or C₇-C₂₀-arylalkylradicals, which can form a ring having 3 to 8 carbon atoms which cancontain hetero atoms; the R⁶ and R⁷ substituents, same or different, arehydrogen, C₁-C₂₀-alkyl, C₃-C₂₀-cycloalkyl, C₂-C₂₀-alkenyl, C₆-C₂₀-aryl,C₇-C₂₀-alkylaryl or C₇-C₂₀-arylalkyl radicals, optionally containingsilicon or germanium atoms; and optionally two adjacent R⁶ and R⁷substituents can form a ring comprising from 5 to 8 carbon atoms; M is atransition metal selected from those belonging to group 3, 4, 5, 6 or tothe lanthanide or actinide groups in the Periodic Table of the Elements(new IUPAC version), X, same or different, is a monoanionic ligand, suchas a hydrogen atom, a halogen atom, an R¹⁰, OR¹⁰, OSO₂CF₃, OCOR¹⁰, SR¹⁰,NR¹⁰ ₂ or PR¹⁰ ₂ group, wherein the substituents R¹⁰ are a C₁-C₂₀-alkyl,C₃-C₂₀-cycloalkyl, C₂-C₂₀-alkenyl, C₆-C₂₀-aryl, C₇-C₂₀-alkylaryl orC₇-C₂₀-arylalkyl radical, optionally containing silicon or germaniumatoms; p is an integer from 0 to 3, p being equal to the oxidation stateof the metal M minus two; and (B1) at least one of an alumoxane and acompound capable of forming an alkyl metallocene cation; wherein thepolymers of alpha-olefins are amorphous.
 17. The composition accordingto claim 16, wherein the ratio of the quantities by weight of thecomponents (A)/(B) is comprised between 10:90 and 90:10.
 18. Thecomposition according to claim 17, wherein the ratio of the quantitiesby weight of the components (A)/(B) is comprised between 30:70 and70:30.
 19. The composition according to claim 16, wherein the amorphouspropylene polymer of component (A) has a melting enthalpy lower than 50J/g.
 20. The composition according to claim 19, wherein the amorphouspropylene polymer of component (A) has a melting enthalpy lower than 20J/g.
 21. The composition according to claim 16, wherein the amorphouspropylene polymer of component (A) has intrinsic viscosity values [η] ofgreater than 0.5.
 22. The composition according to claim 16, wherein incomponent (A) the ratio of the pentads (mmmm)/(rrrr)≧2.0.
 23. Thecomposition according to 16, wherein in component (A) the ratio of thepentads (mmmm)/(mmmr)≧0.9.
 24. The composition according to claim 23,wherein in component (A) the ratio of the pentads (mmmm)/(mmmr)≧1.0. 25.The composition according to claim 16, wherein the amorphous propylenepolymer of component (A) has less than 1% of the CH₂ groups contained in(CH₂)_(n) sequences wherein n=2.
 26. The composition according to claim16, wherein the amorphous propylene polymer of component (A) has aM_(w)/M_(n) ratio of lower than
 4. 27. The composition according toclaim 26, wherein the amorphous propylene polymer of component (A) has aM_(w)/M_(n) ratio of lower than
 3. 28. The composition according toclaim 16, wherein the isotactic propylene polymer of component (B) has amelting enthalpy greater than 90 J/g.
 29. The composition according toclaim 16, wherein the component (B) has the following characteristics:melting point of between 110° C. and 160° C.; [η]>1 dl/g.
 30. Thecomposition according to claim 16, wherein the component (B) is apropylene copolymer having an essentially isotactic structure, which hasthe following characteristics: melting point of between 110° C. and 140°C.; [η]>1 dl/g; fraction soluble in xylene at 25° C. of less than 10%.31. Manufactured articles obtained from a composition according to claim16.
 32. A low-temperature-heat-sealing film obtained from a compositionaccording to claim 16.